Production of organo-tin compounds



Oct. 2, 1951 H. J. PASSING ET AL PRODUCTION 0F ORGANO-TIN COMPOUNDS Filed Deo.

.UDOOmm unDmU me@ u Nrw N EJ U n ll ...0:00am M0510 N .w .u

. .ODDOER uDDmU Patented ct. 2, 19x51 i IIBQDUQTIQNLQFQRGANQF'IlN--COMPOUNDS Herbert .-'ePassinm JLEnglewood, Y.and 4iRussell -11Mantell,Newarki,N. J., assignors to The M. W.

@Kellogg- Company, Jersey-City, YN. J a. corpoveration.012Delasnlaame Appucanqnineember 20, 1s4e,.Seria1No..1a4,1.14

This jinvention' `igrelates to the"productionV of organoetin compounds. In oneraspect ythe iin- .vention 'reletes"to' 'the .nroduetionof .butyltin .chlorides ,particularly idhutyltn diehlorde A"Irn venetherf aspect; the .invention :relates 'to' "the irecovery of ldibutyl tin .eliehlordeifrom @product ,comprisingmonobutyl trohlorde `and .stan- .nouschlorideimpurities.' i

Y VThe. aforementioned product-may be. obtained vbythe interaction ofbutyl .chloride,.stanniczehlo- Yride and rmetallic sodium. `This product v,nor-

mall-y. .eonlprisesedibutylftin diehioriele, `.rnonoloutyl 4.tr.ioh-loiiide .and .Stannous vchlorideand may valso contain, 'dependingv upon the reaction/econ- YditionsghigherY molecular `weight vbutyl ltin compounds such as `tributyl tin fmonochloride, tetrablltyl tinrandfhexabutyl 4di-tm, minor proportions of sodium .chloride and metallic sodium .and possibly somemetallic ;tin. `,Although dibutyl Atin dichloride.isnormallyoasold the reactionrproduct is obtained as Valiquid inasmuch asfrnonobutyl tin v,.ifrichloride, tributyl tin monochloride and .higher .butyl vtin Icompounds which are also `vformed'ar'e normallyliquid. Dibutyl tin d ichlorideflis highlyvaluable for use asa thermal-stef bili'zerwhen incorporated in vinylresrins. Theregfore, itlis Adesirable to recover it from the aforeumentioned reaction product` abscompletely as pps- .sible.

.Heretofore theseperetien .of .-.dibntyl :tin 11i- :3

.-.eh10rid.e fromthe aforementioned reaction `prod- ...uot has 'fbeenobtened by `resortirn; to .distilla- .tion However, .the '.dibntyl :tin .diehloride fracvtion ,thus recovered still contains Y monobutyl tin trichloride, tributyl. tin y.monochlfliride hexabutyll provide ammcees fior Veffiei-entrecovery ofrdibntylj .Me-fl.

. Y Y` 2 i'tin''-rlvichloride in Arelatively #pure #form from a product comprisingmonobutylftintrichlorideand stannous chloride. v`zflnother object ofv ,the "invention, is toprovi'de a1 processfor .eflicient recovery of 'dibutylftin dichloride'inrelatively pure form vfrom aipro'duct .obtained Iby the J'Lntereeton of vbutyl chloride, .Stannc .chloride ,end .metallic sodium. -and .oon- Lteinine .monobutyl ,tin '.trichloride `.and .stennous Qhloride as impurities.

Other objects and advantages inherentin the invention will be apparent to `lzhoseskilled` in the artjrom the .following more detailed disclosure. According yto the v`inventior1. ifn 5itsloroada.Spect asimoreiully hereinafterdescribed', va product Vcomprising .dibutyl itin dichloride' :is treated to reo'overfdibutyl `tin dichloridelby .aseries Y01E steps which Iinclude v(QA) water-Washing a. liguidemi'xture Y':pmprising the dibutyl tin .-dichloride and t Stamious chloride,,to Idissolve stannous .ehloride .theweter and separaten fremitheeibntyl .tin die-blonde; and (13) cooling a .liquid m une of uthe 1i-butyl Vtin.dehlorigleandpcontnnn tleest .one .butyl itin .eomnoundlower :melting than .di- @butyltnvsiichloride to. separate crystals .containing ,dibutyl tin dichloride .and substantiallygfree Hof. lower melting .butyl tin:.compo.unds. These :treatments ,may be applied to .the .zdibutyl .tin di- ,.chloride product Linl either ,order. :If .theyvashing 0 step is applied first andif monobutyl l.tintrichloride is present, a .substantial eproportiornof -the emonobutyl.tinetrichloride v vv/ill be. dissolved Lin the wash water-and recovered Withthe stannousohlo- Vride. -If Athe crystallization `step fis carried out ``lirst, the Water-soluble v monobutyl tin -trichloride uwill'be"separated from-the -dibutyl -tin dichloride andwill' bellargely-removed from the'processjprior @to-the Washing step. Furthermorefithe crystal- -lization step Yis` carried outY first, fit is 'desirable to here a .Solvent present intnennhsequent .Weter- -washing vtreatment vvto facilitate ,contact pf .the A'stennous `chloride with water, or the .,elvstelline mess may .be heated to its meltneintrpriorto yWater-vvashing to l facilitate. such QQntaet k:In .one .embodiment kof this. ,invention the C..aforementioned .product to r.loe V.treated -fierstfob- -.,tainedas .a .crude-liquid-product, produced hyythe .interaction of `vbutyl chloride,- .stannous chloride 50 and m-etallicesodium, comprising fdibutyl `vtin. .di-

-ohloride -monebntyl .tintriehloride,ftributylstin :.monoehloride jand minor .nreportone for tetra- .fbntyltn h xebntyl div-tin ndestennonseehleride,

nets lenprone lens f'ssoslium blonde addition --;this product .:Iney l:.contein eter-vine traces of sodium chloride.

necessitated, inasmuch as direct contact yofthis 4 solid phase material with a suitable solvent for these impurities does not result in their completel absorption or dissolution in the solvent. This condition is encountered by reason that stannous chloride and sodium chloride being in a nely divided state are surrounded by a layer of the crystalline dibutyl tin dichloride in the thus- -formed solid phase which prevents the solvent from coming into contact with the stannous chloride and sodium chloride, so that their absorption by the solvent is not attained. There- Y fore, in order to effect such liquefaction this step I in the drawing, ,to obtain4 a" salt-cake residue comprising essentially Vmost ofthe sodium chloride originally present in the liquid product and minor quantities of stannous. chloride. The remaining filtrate contains V'dibutyltin dichloride,

the lower melting and lower boiling monobutyl tin trichloride and higher molecular Weight butyl tin compounds, the solventlfor -metallic sodium, stannous chloridef in minor proportion and also traces of sodium chloride. If so desired, the saltcake residue may be washed with a suitable relatively low boiling solvent, such as the solvent previously Vemployed'for dissolving the metallic sodium, in order to recover any organo-tin com. pounds contained therein. The resulting filtrate c may be combined with the aforementioned filtrate obtained from theV centrifuging step. The filtrate from the centrifuging step, or the aforementioned combined iiltrates, is next chilled to a temperature suflicientlylow so as to crystallize dibutyl `tin dichloride present, as represented by crystal- Vlization 'step II in the drawing. The temperature thus employed will depend to some extent uponV the boiling point of the relatively high boiling solvent employed in the initial metallic sodium dissolving step and also for the most part upon the ratio of quantity by weight of the solvent to the total reaction product. However, a temperature below at least 0 C. is ordinarily sufficient to effect the aforementioned crystallization of dibutyl tin dichloride, with a temperature of between about C. and about 20 C.

or even lower, being preferred. Following the aforementioned crystallization, dibutyl tin dichloride is obtained as a solid phase and, in adsolvent if employed in the original interaction` step, may, if so desired, be subjected to further purification such as fractional distillation in orderto recover any remaining quantities of dibutyl tin dichloride or other organo-tin compounds contained therein, which may be recycled.

Il'he solid phase material obtained from the aforementioned filtration or separation step I2 is next subjected to liquefaction, represented by step I3 in the drawing, in order to make possible the subsequent solvent treatment for the removal of water-soluble impurities which comprise chieiiy stannous chloride in an amorphous state, some monobutyl tin trichloride and also Such liquefaction is yuid state.

solid phase material is heated to a temperature sufficiently high to put this material into the liq- I-Ience, it is preferred to heat this solid phase material to a temperature between about 0 C. and about 75 C. for this purpose, with a temperature of about 50 C. being preferred. On the other hand, the aforementioned liquefaction step may also be accomplished by contacting the solid phase material with a suitable solvent for fdibutylA tin dichloride, even though such solvent will notbring stannous chloride and other impurities present into solution. Accordingly, the solid phase material may be contacted with a relatively low boiling solvent such as a paraffin, a parafnic petroleum fraction, 40-60 C. petroleum ether, benzene, toluene, xylene, or carbon tetrachloride in an amount sufficient to bring the dibutyl tin dichloride present into solution. Of these solvents it is preferred to employ such relatively low boiling paraiiins as hexane, heptane or octane, and also benzene, in a ratio of about 2 to 3 parts by weight of solvent to the solid residue treated.

The liquid mixture thus obtained, either by the aforementioned heating procedure or solvent contact, is next subjected to suitable water- `washing or extraction treatment for the phase separation of water-soluble impurities present, which comprise monobutyl tin trichloride, stannous Vchloride and traces of sodium chloride, which is represented by water-washing step I4 in the drawing. Thus, the removal of stannous chloride will also effect the removal of monobutyl tin trichlorideand sodium chloride which may be present, while dibutyl tin dichloride and other high `boiling organo-tin compounds present will not be dissolved. Therefore, the waterwashing of the liquid mixture obtained from the aforementioned liquefaction step I3 will bring the water-soluble impurities into the aqueous phase which is formed, while dibutyl tin dichloride and higher organo-tin compounds such as tributyl tin monochloride, tetrabutyl tin and hexabutyl di-tin are obtained in the waterinsoluble or yorganic phase. y

The aforementioned Water-washing treatment of the liquid mixture obtained from step I3, while effecting the absorption of stannous chloride and other water-soluble impurities present may also result in the mixture thus obtained forming an emulsion, and in some instances. may cause the desired dibutyl tin dichloride end-product and other tin compounds present to hydrolyze. In order to prevent such emulsiiication of the mixture or hydrolysis of dibutyl tin dichloride and other tin compounds present from taking place, it has been found desirable to acidify thewashwater with an acid, which is preferably an inorganic mineral acid such as hydrochloric acid or sulfuric acid. In thisrespect, it is preferred that the-aqueous solution ofthe Linorganic mineral acid `be employed in-an-amount between from the remaining higher organo-tin compounds (and solvent, if'employed for purposes of liquefying the solid phase'H material in liquefaction step'l3). Accordingly, this material is next chilled to a temperature sufficiently low so as to crystallize the dibutyl tindichloride component present, which is represented by recrystallization step I5 in the drawing. This recrystallization may be effected 'by employing similar suitable temperature conditions as employed in the primary crystallization step I'I, and in general is satisfactorily performed at a temperature below kat least C., with temperatures Ibetween about C. and about 20 C., or even lower, being preferred. Following the above-mentioned recrystallization step, substantially pure dibutyl tin dichloride is'obtained in the crystalline state, While the other organo-tin components are obtained in the liquid state, or as a solvent phase if a solvent has been previously employed in the liquefaction of the solid phase material in step I3. This chilled mixture is next treated, as represented by ltration step I6 in the'drawing, to effect the separation ofthe dibutyltin dichloride crystals from the liquid material. This liquid, or solvent phase material, is withdrawn from the crystalline dibutyl tin dichloride residue and may be subjected to further processing or puriication for the recovery of the solvent or other organo-tin compounds present. The remaining crystalline dibutyl tin dichloride residue may then be subjected to suitable drying treatment, represented by dryingstep I1 in the drawing, to eiect the recovery of substantially pure dibutyl tin dichloride as a vproduct of the process. In some instances, depending upon the conditions under which the primary interaction of butyl chloride, stannic chloride and sodium has taken place, undesirable color bodies may be foundV in the product thus produced which would impair the appearance of the. final dibutyl tin dichloride end-product obtained. Where such is the case, the removal of these color bodies may be accomplished through the use ofV suitable adsorption media such as activated alumina,

bauxite or treated clays, prior to the aforementioned recrystalization step I5. 'Thus the organic phase obtained from water-washing step I4 may be passed through the aforementioned adsorption media for the removal 'of these color bodies, and the remaining liquid mixture is then subjected to recrystallization in step I5. In the present embodiment of the invention, as illustrated by Figure 1 of the drawing, it will thus be noted that the essential water-washing and cooling steps, as previously indicated, are applied by carrying out the cooling or crystallization step first' (represented by step II), followed by the water-washing step (represented by step I4).

`Accordingto another embodiment of the invention, as illustrated by Figure 2 of the ldraw- 6 ing, the .aforementioned liquid product obtained by the interaction of butyl chloride, stannic chloride and metallic sodium is also rst centrifuged to obtain a salt-cake residue, as represented by step I8 in the drawing, and comprising essentially sodium chloride and minor quantities of stannous chloride, and a filtrate comprising dibutyl tin dichloride, monobutyl tin trichloride and higher organo-tin compounds, the solvent for metallic sodium (if employed in the original interaction step) stannous chloride in minor proportions and traces of sodium chloride. However, in this embodiment ofthe invention, the ltrate thus obtained is subjected to waterwashing treatment, represented by step I9 in the drawing, which may be eected by employing 'an aqueous solution of an inorganic mineral acid 'such as employed in the water-washing step yI4 in the previous embodiment represented by Figure 1 in the drawing, in order to effect the phasefse'paration of water-soluble impurities which 'comprise substantially all of the stannous chloride, sodium chloride and monobutyl tin trichloride present, from dibutyl tin dichloride, solvent and higher organo-tin compounds which are obtained in the organic phase, and which separation is effected without the aforementioned hydrolysis of dibutyl tin dichloride and higher organo-tin compounds taking place. The aqueous phase thus obtained may be subsequently subvjected to suitable purification treatment for the recovery of monobutyl tin trichloride if so desired, but which is outside the scope of the present process.

The water-insoluble organic phase obtained from the above-mentioned water-washing treatment and comprising dibutyl tin dichloride and higher organo-tin compounds and solvent is next chilled to a temperaturek suiliciently low so as to crystallize the dibutyl tin dichloride component present, which is represented by crystallization step 20 in the drawing, and which may be effected under similar temperature conditions as employed in crystallization step Il in the previous embodiment represented by Figure 1 of the present process. Following this crystallization, substantially pure dibutyl tin dichloride is obtained in the crystalline state, while the other organotin compounds and solvent are obtained in the liquid state. This chilled mixture is next treated to effect the separation of dibutyl tin dichloride crystals from the liquid mixture and is represented by filtration step 2| in the drawing. The liquid phase material or filtrate is next withdrawn from the crystalline dibutyl tin dichloride residue and may be subjected to further processing or purication for the recovery of higher organo-tin compounds and solvent present. The remaining crystalline dibutyl tin dichloride residue may then be subjected to suitable drying treatment, represented by drying step 22 in the drawing, to effect the recovery of substantially pure dibutyl tin dichloride as a product of the process. In this embodiment of the invention, as illustrated by Figure 2 of the drawing, it will thus be noted that the essential water-washing and cooling steps, as previously indicated, are applied by carrying out the waterwashing step first (represented by step I9), followed by the cooling or crystallization step (represented by step 20) According to still another embodiment of the invention, as illustrated by Figure 3 in the drawing, the liquid product obtained by the interaction of butyl chloride, stannic chloride and metallic sodium is water-washed directly after the interaction of the aforementioned components, without prior centrifuging or separation of a salt-cake residue comprising essentially sodium chloride, stannous chloride and tin, as effected in the previous embodiments. Accordingly, this liquid reaction product is subjected to waterwashing treatment, as represented by step 23 in the drawing, and which may be effected by employing an aqueous solution of an inorganic mineral acid such as employed in water-washing steps I4 and i9 in the previous embodiments represented by Figures 1 and 2, respectively. This water-washing treatment results in the phase separation of water-soluble impurities comprising substantially all of the stannous chloride, sodium chloride and monobutyl tin trichloride present from dibutyl tin dichloride, higher organo-tin compounds and solvent which are obtained in the organic phase. The aqueous phase may be subjected to suitable purication treatment for the removal of monobutyl tin trichloride, if so desired, by processes which are outside the scope of the present invention.

The water-insoluble organic phase obtained from the aforementioned water-washing treatment and comprising dibutyl tin dichloride, higher organo-tin compounds and solvent, is next chilled to a temperature sufficiently low so as to crystallize the dibutyl tin dichloride component present, which is represented by crystallization step 2d in the drawing, and which may be effected under similar temperature conditions as employed in crystallization steps il and 20 in the previous embodiments of the present process, represented by Figures 1 and 2, respectively. Following this crystallization, substantially pure dibutyl tin dichloride is obtained in the crystalline state, while the other organo-tin compounds and solvent are obtained in the liquid state This chilled mixture is next treated to eiect the separation of dibutyl tin dichloride crystals from the liquid mixture, and is represented by iltration step 25 in the drawing. The liquid phase material or filtrate is next withdrawn from the crystalline dibutyl tin dichloride residue and may be subjected to further processing or purication for the recovery of higher organo-tin compounds and solvent present. 'Ihe remaining crystalline dibutyl tin dichloride residue may then be subjected to suitable drying treatment, represented by drying step 26 in the drawing, to effect therecovery of substantially pure dibutyl tin dichloride as a product of the process. In this embodiment of the invention, as illustrated by Figure 3 of the drawing, it will thus be noted that the essential water-washing and cooling steps, as previously indicated, are applied by carrying out the waterwashing step rst (represented by step 23), followed by the cooling or crystallization step (represented by step 24).

Ve claim:

l. In a process for producing dibutyl tin dichloride wherein reagents are interacted to produce a liquid product mixture comprising said dibutyl dichloride, stannous chloride and at least one butyl tin compound lower melting than dibutyl tin dichloride, the method for recovering a relatively pure dibutyl tin dichloride product which comprises the step of washing a liquid mixture comprising said dibutyl tin dichloride and stannous chloride with water to dissolve stannous chloride in the water and separate it from dibutyl tin dichloride, and the step of cooling a liquid mixture comprising said dibutyl tin dichloride and said butyl tin compound to sepand stannous chloride with water to dissolve stannous chloride in the water and separate it from dibutyl tin dichloride, and the step of cooling a liquid mixture comprising said dibutyl tin dichloride and monobutyl tin trichloride to separate crystals containing dibutyl tin dichloride and substantially free from monobutyl tin trichloride.

3. In a process for producing dibutyl tin dichloride Wnerein reagents are interacted to produce a liquid product mixture comprising said dibutyl tin dichloride, stannous chloride and at least one butyl tin compound lower melting but higher boiling than dibutyl tin dichloride, the method for recovering a relatively pure dibutyl tin dichloride product which comprises the step of washing a liquid mixture comprising said dibutyl tin dichloride and stannous chloride with water to dissolve stannous chloride in the water and separate it from dibutyl tin dichloride, and the step of cooling a liquid mixture comprising said dibutyl tin dichloride and said butyl tin compound to separate crystals containing dibutyl tin dichloride and substantially free from said butyl tin compound.

4. in a process for producing dibutyl tin dichloride wherein reagents are interacted to produce a liquid product mixture comprising said dibutyl tin dichloride, tributyl tin monochloride and stannous chloride, the method for recovering a relatively pure dibutyl tin dichloride product which comprises the step of washing a liquid mixture comprising said dibutyl tin dichloride and stannous chloride with water to dissolve stannous chloride in the water and separate it from dibutyl tin dichloride, and the step of cooling a liquid mixture comprising said dibutyl tin dichloride and tributyl tin monochloride to separate crystals containing dibutyl tin dichloride and substantially free from tributyl tin monochloride.

5. In a process for producing dibutyl tin dichloride wherein reagents are interacted to produce a liquid product mixture comprising said dibutyl tin dichloride, stannous chloride and at least one butyl tin compound lower melting than dibutylrtin dichloride, the method for recovering a relatively pure dibutyl tin dichloride product which comprises the step of washing a liquid mixture comprising said ydibutyl tin dichloride and stannous chloride with water in the presence of a solvent for dibutyl tin dichloride to dissolve stannous chloride in the water and separate it from dibutyl tin dichloride, and the step of cooling a liquid mixture comprising said dibutyl tin dichloride and said butyl tin compound to separate crystals containing dibutyl tin dichloride and substantially free from said butyl tin compound.

6. In a process for producing dibutyl tin dichloride ywherein butyl chloride, stannic chloride and metallic sodium are interacted to produce a liquid product mixture comprising said dibutyl tin dichloride, stannous chloride and at least one butylgtin compound, l lower melting than kdibutyl -tirrdichloride; the method forrecovering a relatively-puret dibutylv tin-dichloride productwhich comprises the step off WashingV a y liquidl mixture compri-sing'said dibutyl' tin dichlorideand stannousI chloride with'A water' tol dissolve stannous chloride in the water and separate it from dibutyl tin 'dichloride,-and the step of cooling a liquidf mixture'comprisingf said dibutyl tin-dichlorideand saidv butyl tin compound to separate crystals containing' dibutyl tin dichlorideand substantially free-frorrl said `butyl tin compound.

7.' In a process for producing dibutyl tin dichloride whereinbutyl chloride, stannic'chloride and metalli'c'sodiumA arefinter'acted toproduce a liquid product mix-ture comprising` said dibutyl tin dichloride;l stannous chlorideand at least one butyl tin'y compound lowerfmelting but higher boiling than dibutyl tindichloride, they method for recovering a relatively pure dibutyl tin dichloride product which comprises thevstep of washing a liquid mixture comprising said dibutyltin dichloride and stannous .chloride with water-to dissolve stannous chloride in the water and separate it from dibutyl tin dichloride, and the step oiicoolingaliquidl` mixture comprising said dibutyl tin dichloride and said butyl tincompound to separate crystals containing dibutyl tin dichloride and substantially free from said butyl tin compound.

8. In a. process for producing dibutyl tin dichloride wherein butyl chloride, stannic chloride and metallic sodium are interacted to produce a liquid product mixture comprising said dibutyl tin dichloride, stannous chloride and at least one butyl tin compound lower melting than dibutyl tin dichloride, the method for recovering a relatively pure dibutyl tin dichloride product which comprises the step of washing a liquid mixture comprising said dibutyl tin dichloride and stannous chloride with water in the presence of a solvent for dibutyl tin dichloride to dissolve stannous chloride in the water and separate it from dibutyl4 tin dichloride, and the step of cooling a liquid mixture comprising said dibutyl tin dichloride and said butyl tin compound'A to separate crystals containing dibutyl tin dichloride and substantially free from said butyl tin compound.

9. In a process for producing dibutyl tin dichloride Iwherein reagents are interacted to produce a liquid product mixture comprising said dibutyl tin dichloride, monobutyl tin trichloride and stannous chloride, the method for recovering a relatively pure dibutyl tin dichloride product which comprises the steps of cooling a liquid mixture comprising said dibutyl tin dichloride, stannous chloride and monobutyl tin trichloride to form a solid phase comprising stannous chloride and crystals of dibutyl tin dichloride substantially free from monobutyl tin trichloride, separating said solid phase from said liquid mixture, liquefying said solid phase, and washing said liquefled phase with water to dissolve stannous chloride in the water and separate it from dibutyl tin dichloride.

10. In a process for producing dibutyl tin dichloride wherein butyl chloride, stannic chloride and metallic sodium are interacted to produce a liquid product mixture comprising said dibutyl tin dichloride, monobutyl tin trichloride and stannous chloride, the method for recovering a relatively pure dibutyl tin dichloride product which comprises the steps of cooling a liquid mixture comprising said dibutyl tin dichloride, stannous chloride and monobutyl tin trichloride to form a solid phase comprising stannous chloride and 10 crystals of dibutyl-tin dichloride substantially free from monobutyl tin trichloride, separating said-solid phase from said'liqui'd mixture, liquefying said solid phase, and washing said-liquefied phase With water to dissolve stannous chloride in the water and-separate it from dibutyl tin dichloride.

11. In a process for producing dibutyl tin dichloride wherein reagents are interacted to produce a liquid product mixture comprising said dibutyl tin dichloride, monobutyl ti'n trichloride andv stannous chloride, the method for recovering-a relatively pure dibutyl tin dichloride product whichcomprises the stepsof washing a liquid mixture comprising said dibutyl tin dichloride, stannous chloride and -monobutyl tin trichloride withwater to form an organic liquidbase comprising dibutylftinY dichloride and an aqueous phase comprising monobutyl tin trichloride and stannous chloride,- separating said phases, coolingY said organic phase to form a-solid vphase comprising crystals of dibutyl tin dichloridesubstantiallyl free from said monobutyl tin trichloride, and separating said solid phase-from -saidorganic phase. A

12. In a process for producing dibutyl tin dichloride wherein butyl chloride, stannic-chloride and metallic sodium are interacted to produce a liquid product mixture comprising said dibutyl tin dichloride, monobutyl tin trichloride and stannous chloride, the method for recovering a relatively pure dibutyl tin dichloride product which comprises the steps of washing a liquid mixture comprising said dibutyl tin dichloride, stannous chloride and monobutyl tin trichloride with water to form an organic liquid phase comprising dibutyl tin dichloride and an aqueous phase comprising monobutyl tin trichloride and stannous chloride, separating said phases, cooling said organic phase to form a solid phase comprising crystals of dibutyl tin dichloride substantially free from said monobutyl tin trichloride, and separating said solid phase from said organic phase.

13. In a process for producing dibutyl tin dichloride wherein butyl chloride, stannic chloride and metallic sodium are interacted to produce a liquid product mixture comprising said ditutyl tin dichloride, monobutyl tin trichloride and stannous chloride, the method for recovering a relatively pure dibutyl tin dichloride product which comprises the steps of cooling said liquid product to a temperature below about 0 C. to form a solid phase comprising stannous chloride and crystals of dibutyl tin dichloride substantially free from monobutyl tin trichloride, separating said solid phase from said liquid product, contacting said solid phase with a solvent for dibutyl tin dichloride in a weight ratio of approximately 2:3 to form a, liquid mixture comprising dibutyl tin dichloride and stannous chloride, washing said liquid mixture with an aqueous solution of an inorganic mineral acid in an amount between about 10% and about 15% by Weight of said liquid mixture to form an organic phase comprising dibutyl tin dichloride and solvent and an aqueous phase comprising stannous chloride, separating said phases, cooling said organic phase to a temperature below about 0 C. to form a solid phase comprising crystals of dibutyl tin dichloride and a liquid phase comprising solvent, and separating crystals containing dibutyl tin dichloride from said liquid phase.

14. In a process for producing dibutyl tin dichloride wherein butyl chloride, stannic chloride and metallic sodium are interacted to produce a liquid productmixture comprising said dibutyl tin dichloride, monobutyl tin trichloride and stannous chloride, the method for recoveringa relatively pure dibutyl tin dichloride product which comprises the steps of washing a, liquid mixture comprising said dibutyl tin dichloride, stannous chloride and monobutyl tin trichloride with an aqueous solution of an inorganic mineral acid in an amount between about 10% and about 15% by Weight of said liquid Ymixture to form an organic liquid phase comprising dibutyl tin dichloride and an aqueous phase comprising monobutyl tin trichloride and stannous chloride, separating said phases, cooling said organic phase to a temperature below about C'. to form a solid phase comprising crystals of dibutyl tin dichloride substantially free from said monobutylV tin trichloride, and separating said solid phase :from

said organic phase.

15. In a process for producing dibutyl tin dichloride wherein butyl chloride, stannic chloride and metallic sodium are interacted to produce a liquid product mixture comprising said dibutyl tin dichloride, monobutyl tin trichloride and stannous chloride, the method for recovering a relatively pure dibutyl tin dichloride product which comprises'the steps of washing the Vtotal product of said interaction comprising said dibutyl tin dichloride, stannous chloride and monorbutyl tin trichloride with an aqueous solution of an inorganic mineral acid in an amount between about 10% and about 15% by Weight of said liquid mixture to form an organic liquid phase comprising dibutyl tin dichloride and an aqueous phase comprising monobutyl tin trichloride and stannous chloride, separating said phases, cooling said organic phase to a temperature below about 0 C. to form a solid phase `comprising crystals of dibutyl tin dichloride substantially free from said monobutyl tin trichloride, and separating said solid phase from said organic phase.

HERBERT J. PASSING. RUSSELL M. MANTELL.

REFERENCES CITED.

UNITED STATES PATENTS Name Date Harris Nov. 18,. 1947 Number 

1. IN A PROCESS FOR PRODUCING DIBUTYL TIN DICHLORIDE WHEREIN REAGENTS ARE INTERACTED TO PRODUCE A LIQUID PRODUCT MIXTURE COMPRISING SAID DIBUTYL TIN DICHLORIDE, STANNOUS CHLORIDE AND AT LEAST ONE BUTYL TIN COMPOUND LOWER MELTING THAN DIBUTYL TIN DICHLORIDE, THE METHOD OF RECOVERING A RELATIVELY PURE DIBUTYL TIN DICHLORIDE PRODUCT WHICH COMPRISES THE STEP OF WASHING A LIQUID MXITURE COMPRISING SAID DIBUTYL TIN DICHLORIDE AND STANNOUS CHLORIDE WITH WATER TO DISSOLVE STANNOUS CHLORIDE IN THE WATER AND SEPARATE IT FROM DIBUTYL TIN DICHLORIDE, AND THE STEP OF COOLING A LIQUID MIXTURE COMPRISING SAID DIBUTYL TIN DICHLORIDE AND SAID BUTYL TIN COMPOUND TO SEPARATE CRYSTALS CONTAINING DIBUTYL TIN DICHLORIDE AND SUBSTANTIALLY FREE FROM SAID BUTYL TIN COMPOUND. 